A conventional selective call device, e.g., a selective call receiver or a transmitter and a selective call receiver, often can receive messages from more than one source. Sources are distinguished from each other typically by an address information associated with each message. When the address information correlates, or matches, a predetermined address in the selective call device, the selective call device receives and stores the message from a particular information source.
Modern selective call service providers are capable of sending multiple types of data including information services, for example, news, stock market data, weather forecasts, and sport scores, periodically to a subscribing selective call device. However, there is usually a need to transmit updates to previously transmitted information services data.
In general, an information service message is more lengthy than a personal message. However, in many instances, information service messages are repetitive of a prior information service message but for a relatively small portion of changed or new data. Information service messages include both headers and numerical data together and often only the numerical data changes from one information service message to the next. For example, when transmitting stock price information, the stock name, year high and year low information will change much less frequently than the stock's current trading price. As other examples, both sports scores and weather information service messages comprise, in one part, information that is updated on an infrequent basis such as team names or geographic data. Correspondingly, another part of such information service messages comprises information that is frequently updated such as team scores and atmospheric conditions.
In order to reduce airtime, known methods and systems of updating information services messages transmit only a predetermined portion of an information service message. The predetermined portion is that portion which frequently changes. A remaining portion, or template, is that portion which seldom changes. However, after a passage of time, typically after one day, there occurs a need to make a change within the template or to change the size of the template. This is usually accomplished through the use of a new template message For example, if the information service subscribed to is sports scores, the name of the teams will usually change once per day, but the scores will usually change many times per day. It is possible that a selective call device is out-of-range and does not receive the new template message transmitted for the purpose of changing the name of a sports team. Disadvantageously, with known systems and methods, updates, such as a current score of a game, sent to a selective call device that had failed to receive the new template message will continue to be received by the selective call device and be displayed next to the wrong team name.
It is well known to transmit one or more information services sub-messages embedded within a message of a conventional selective call protocol. It is also well known that paging systems do not always transmit messages in the order that the messages were submitted to the paging system; therefore, an embedded information services sub-message will occasionally be received by a selective call device out of sequence. It is usually not of critical importance that conventional personal paging messages be received by a selective call device in the exact order that they were submitted to the paging system because personal messages are typically submitted by different persons or have no special relationship to other personal messages. However, with many information services messages, such as stock prices, the sequence of receiving information services sub-messages is very important because the exact sequence itself conveys important and useful information, such as whether a stock is continually rising in price. With known systems and methods, if an older information services update message is transmitted subsequent to a newer information services update message, the older update will be received and incorrectly displayed by a selective call device as a more recent update.
Thus, what is needed are a method of reliably sending updates to multiple information services sub-messages, or topics, after a change has been made in the template, and a method of recognizing updates received out-of-sequence.